JP2010208308A - Decorative sheet and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a decorative sheet which suppresses change in a design such as whitening and cracking in folded parts upon post processing as much as possible with the use of a polypropylene resin and to provide a method for manufacturing the same. <P>SOLUTION: A transparent polypropylene resin layer includes a homopolypropylene resin (A) having an isotactic pentad ratio of 75% or below and a copolymer (B) of propylene and ethylene or an α-olefin of 3 to 20 carbon atoms, a ratio of (A)/(B) is 50/50 to 95/5, and the copolymer (B) of propylene and ethylene or an α-olefin of 3 to 20 carbon atoms has Shore A hardness of 65-90, a melting point of 130-170°C, a density of 860-875 kg/m<SP>3</SP>and a glass transition point of -35 to -25°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a decorative sheet used as a steel sheet decorative plate by being bonded to the surface of a metal plate, an aluminum plate or the like with an adhesive, and a method for manufacturing the decorative sheet.

  Conventionally, as a decorative sheet used for a decorative board, a sheet made of a polyvinyl chloride resin has been most common. In recent years, however, polyvinyl chloride resin has become a cause of the generation of hydrogen chloride gas and dioxin, a highly toxic substance, which causes acid rain during incineration, and further due to the bleed-out of plasticizer added to the sheet made of polyvinyl chloride resin. There are also problems such as deterioration in designability, and it has been regarded as a problem from the viewpoint of environmental protection. From the background as described above, there has been a demand for decorative sheets using non-vinyl chloride resins such as polypropylene, polyethylene and acrylic.

Under such circumstances, decorative sheets using resins such as polyethylene, polypropylene, polyethylene terephthalate, ethylene vinyl alcohol, and acrylic as a resin replacing vinyl chloride resin have been proposed and marketed.

  Among them, it has moderate flexibility required for decorative sheets, abrasion resistance, scratch resistance, heat resistance, chemical resistance, workability after bonding to steel plate base materials, etc., and is provided at low cost. A large number of decorative sheets using polypropylene are proposed.

  However, polypropylene also has some drawbacks. The main drawbacks are that the resistance to ultraviolet rays is not high, and that the other is because polypropylene is a crystalline resin, so crystal growth occurs due to thermal history such as molding conditions and ambient atmosphere after molding. This will change the way the material changes, affecting the mechanical properties of the material. In the first place, since the degree of crystallinity of polypropylene resin tends to be high, compared to other olefin materials, the rigidity of molded products tends to be high, and the workability after bonding to a steel plate substrate is not very good. There is a high possibility that the mechanical physical properties may exceed the allowable range and swing in a bad direction.

  Among the above-mentioned drawbacks, as a measure for improving ultraviolet resistance, a method of providing a surface protective layer using a gravure coating method or the like is generally used, and furthermore, a polypropylene resin that cannot be laminated by a gravure coating method. It is known to apply a technique such as wiping to protect the concave portion of the conduit provided by embossing the layer. (Patent Document 1) However, even in this method, an extra step for wiping must be performed, and it is difficult to control the thickness of the surface protective layer in the conduit.

In addition, the problem of workability after being bonded to the latter steel sheet base material is a form in which the folded portion of the decorative sheet is whitened or cracked, for example, in the bending process of the decorative sheet bonded with the decorative sheet. It may become obvious. Until now, a method using a homopolypropylene resin having a low isotactic pentad fraction with reduced stereoregularity in the transparent resin layer (Patent Document 2) or adding an elastomer component to polypropylene (Patent Document 3) Methods have been proposed.

  However, even when such measures are taken, depending on the bent shape and the environmental atmosphere, the workability after bonding to a steel plate substrate may not reach a sufficient level yet, and further improvements can be made. It has been demanded. In addition, in the conventional method, there is sufficient workability after bonding to a steel plate substrate in bending in the film forming direction, but sufficient steel plate substrate in bending in the direction perpendicular to the film forming direction. In some cases, it was not possible to obtain the workability after bonding to the same.

Japanese Patent No. 3271102 JP 2006-7688 A JP 2006-56128 A

  The present invention has been made in order to solve the above-mentioned problems, and the object of the present invention is to use a polypropylene resin as a material and design such as whitening and cracking of a bent portion at the time of post-processing. It is to provide a decorative sheet that suppresses the above change as much as possible and a method for producing the same.

The present invention solves the above-mentioned problem, that is, the invention according to claim 1 is a decorative sheet comprising at least a pattern layer, a transparent polypropylene resin layer, and a surface protective layer in this order on a base sheet. (1) The transparent polypropylene resin layer has an isotactic pentad fraction of 75%, which is defined as the number of propylene monomers / propylene monomer number x 100 [%] in which five methyl groups are continuous in the same direction. It consists of the following homopolypropylene resin (A) and a copolymer (B) composed of propylene and ethylene or an α-olefin having 3 to 20 carbon atoms, and the blending ratio of (A) and (B) is 50 / (2) A copolymer (B) comprising propylene and ethylene or an α-olefin having 3 to 20 carbon atoms has a Shore A hardness (AST -D2240) is 65 to 90, a melting point of 130 to 170 ° C., a density (ASTM-D1505) is the 860~875kg ^/ m 3, the glass transition temperature by DSC measurement is -35 ℃ ~-25 ℃, ( 3) the A transparent polypropylene resin layer is a decorative sheet comprising a biaxially stretched sheet.

  The invention according to claim 2 is the decorative sheet according to claim 1, wherein the decorative sheet has a total thickness of 40 to 300 μm.

  The invention according to claim 3 is that the transparent polypropylene resin layer is extruded from the T-die by a biaxial stretching method, and then stretched in a film forming direction and a direction perpendicular to the film forming direction. It is a manufacturing method of the decorative sheet in any one of Claim 1 or 2.

  The invention according to claim 4 is the decorative sheet according to claim 3, wherein the transparent polypropylene resin layer is subjected to a concave embossed pattern treatment from the surface side after the stretching treatment. It is a manufacturing method.

  According to the first aspect of the present invention, a resin that satisfies the above conditions (1) and (2) is selected and made into a biaxially stretched sheet, so that it becomes rich in flexibility.

  Further, according to the invention described in claim 2, when the total thickness is 40 to 300 μm, the physical properties and economics of the decorative sheet described in claim 1 can be balanced.

  Further, according to the invention described in claim 3, by performing biaxial stretching after extrusion, the transparent polypropylene resin has a film forming direction (hereinafter referred to as “MD direction”) and a direction perpendicular to the film forming direction ( Hereinafter, it is referred to as “TD direction”). As a result, the toughness in the MD direction and TD direction of the transparent polypropylene resin layer is increased, and when the post-processing such as bending is performed by bonding to a steel plate substrate, the design of whitening or cracking of the bent portion is performed. Changes are suppressed.

  According to the invention described in claim 4, the recessed embossed pattern is not deformed by stretching by performing the recessed embossed pattern processing from the surface side after the biaxial stretching process. Flexibility is imparted by using this transparent polypropylene resin, and since toughness is imparted by biaxial stretching, it has a feature that whitening, cracking, opening, etc. are difficult to occur.

It is explanatory drawing which shows the structure of the cross section of one Example of the decorative sheet of this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows a cross-sectional structure of one embodiment of the decorative sheet of the present invention. On the substrate sheet 1 used as appropriate, it has a pattern layer 2, an adhesive layer 3 provided as appropriate, a transparent polypropylene resin layer 4, a recessed embossed pattern 5 provided as appropriate, and a surface protective layer 6.

  As the base sheet 1 in the present invention, polypropylene, polyethylene, ethylene vinyl acetate copolymer resin, ethylene vinyl alcohol copolymer resin, polystyrene, ABS, polymethyl methacrylate, polymethyl acrylate, polybutyl acrylate, polyvinyl acetate Specific examples include sheets made of non-vinyl chloride resin materials such as polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, polyamide, nylon 6 and nylon 66. Can be mentioned. Among these, considering recyclability, a base sheet made of a polyolefin material such as polypropylene or polyethylene is desirable. Furthermore, if the base sheet is made of a polypropylene material, most of the components of the decorative sheet are made of a polypropylene material. Therefore, although it is still desirable, it is not necessarily limited to this.

  In addition, it is possible to add one or more additives such as an inorganic pigment, an antioxidant, a light stabilizer, and an antiblocking agent in an appropriate amount to the resin constituting the base sheet 1. It is.

  The inorganic pigment is added to conceal the base sheet 1. The reason for concealing is to prevent a base material such as a wooden board, an inorganic board, or a metal plate to be bonded from being visible from the surface of the decorative sheet. However, this is not the case when it is desired to make use of the texture of the base material.

  Further, when the T-die extrusion method is used as a method for producing the base sheet 1, a synthetic resin material for forming the film is directly colored with a concealing colorant such as a dye or a pigment and heated and melted. The substrate sheet 1 obtained by extrusion from the T die may be colored to impart concealability.

  In this case, the coloring method of the base sheet 1 in the T-die extrusion method includes a dry color method and a master batch method, but is not particularly limited. In the dry color method, a fine powdery colorant obtained by treating a pigment with a dispersion aid or a surfactant is directly mixed into an ordinary uncolored synthetic resin material for forming the base sheet 1. This is a method of coloring. On the other hand, in the master batch method, a master batch pellet in which a normal synthetic resin material that is not colored for forming the base sheet 1 and a high concentration pigment is melt-kneaded and pre-dispersed is prepared in advance. In the extrusion hopper, this master batch pellet is dry blended with a normal uncolored synthetic resin material for forming the base sheet 1 into a film.

  The types of pigments used for coloring may be those usually used, but inorganic pigments such as titanium oxide, ultramarine, cadmium pigment, iron oxide and the like are particularly desirable in consideration of heat resistance and weather resistance. Also, organic pigments such as phthalocyanine pigments and quinacridone pigments can be used. The pigment-to-resin ratio and hue are appropriately determined in view of the degree of concealment and design properties, and are not particularly limited.

  The pattern layer 2 in the present invention is generally provided on the base sheet 1 using a known printing ink by a known printing method such as gravure printing, intaglio printing, flexographic printing, silk printing, electrostatic printing, and inkjet printing. However, this is not necessarily the case. In addition, the ink used at this time is also known, that is, a colorant such as a dye or pigment or an extender pigment is added to the vehicle, and further, a plasticizer, a stabilizer, a wax, a grease, a desiccant, a curing agent, a thickener. Ink formed by arbitrarily adding a dispersant, a filler and the like and kneading sufficiently with a solvent, a diluent and the like may be used.

  In addition, a concealing layer and / or a pattern layer are formed on the transfer base sheet other than the base sheet 1 for the decorative sheet by the forming method, and the above-described thermal laminating method. Then, after laminating with the base sheet 1 by a dry laminating method, a wet laminating method, an extrusion laminating method or the like, the transfer base sheet is peeled off and the pattern layer 2 is transferred onto the base sheet 1 A method can also be used.

  As a method for applying the pattern layer 2 to the base sheet 1, there are a method for applying to the surface of the base sheet 1 and a method for applying to the base sheet 1 itself (in the layer of the sheet 1). As a method for applying to the surface, the printing method or the transfer method as described above can be used. As a method for applying to the base sheet 1 itself, a master batch pellet in which a high-concentration pigment is melt-kneaded in a resin having different flow characteristics from the resin constituting the base sheet 1 and predispersed, or wood powder, glass powder, etc. Is added to the synthetic resin material provided with concealability for forming the base sheet 1 and heated and melted, extruded and formed into a master batch pellet on the concealable base sheet 1 itself. There is also a method of imparting a pattern with wood powder or glass powder. Of course, these methods of imparting color hiding properties and patterns to the substrate sheet 1 itself can be used in combination with the printing method and transfer method described above.

  Further, when the calendar method is used as a method for producing the concealable base sheet 1, the same method, that is, while the base sheet 1 is produced by the calender method, the base sheet 1 itself is simultaneously colored and concealed. The concealability and the pattern can be imparted to the base sheet 1 by a method of imparting a pattern, or a method using these methods in combination with the above-described printing method, transfer method and the like.

  In the decorative sheet of the present invention, a primer coat layer laminated on the back surface of the decorative sheet is also suitably used (not shown) as necessary in order to increase the adhesion to the steel sheet substrate or the like.

  The adhesive layer 3 provided as appropriate is appropriately selected and provided in order to improve interlayer adhesion between the base sheet 1 provided with the pattern layer 2 and a transparent polypropylene resin layer 4 described later. It can be provided using a known method such as a coating method.

  As the transparent polypropylene resin layer 4 in the present invention, a copolymer (A) having a isotactic pentad fraction of 75% or less and propylene and ethylene or an α-olefin having 3 to 20 carbon atoms ( B) is used, and those having a blending ratio of 50/50 to 95/5 are used.

  The isotactic pentad fraction is defined as five consecutive propylene monomers / number of propylene monomers / number of propylene monomers × 100 [%]. The isotactic pentad fraction is determined as follows: It is measured by a method using 13 C-NMR as described and described by Zambelli et al., Macromolecules, 6, 925 (1973). However, regarding the attribution of the absorption peak of NMR, Macromolecules, 8, 687 (1975), etc., which was published thereafter, can be used as a reference. Specifically, the isotactic pentad fraction is measured as the area fraction of the mmmm peak in the total absorption peak in the methyl carbon region of the 13C-NMR spectrum.

  The homopolypropylene resin (A) having an isotactic pentad fraction of 75% or less used in the present invention preferably has a melting peak temperature (Tm) measured by a differential scanning calorimeter (DSC) of 150 ° C. or higher. Usually, it is 150-165 degreeC. If it is lower than 150 ° C., the heat resistance is insufficient. Furthermore, the melting enthalpy (ΔH) measured by DSC is desirably 100 J / g or less. When it exceeds 100 J / g, flexibility is impaired, and bending resistance and cold shock resistance are deteriorated. Moreover, since there exists a possibility that intensity | strength may become inadequate when (DELTA) H is too small, the range of more preferable (DELTA) H is 10-100 J / g. Furthermore, it is preferable that the boiling n-heptane soluble content is 7 to 50% by weight. If it is less than 7% by weight, the flexibility is insufficient, and the bending resistance and cold shock resistance may be deteriorated. If it exceeds 50%, sufficient mechanical strength and heat resistance cannot be obtained. Furthermore, in order to obtain a better balance of flexibility, mechanical strength, and heat resistance, the boiling n-heptane soluble content is more preferably 10 to 40% by weight.

  Furthermore, the homopolypropylene resin (A) having an isotactic pentad fraction of 75% or less used in the present invention preferably has a melt flow rate (MFR) in the range of 0.1 to 50 g / 10 min. The melt flow rate (MFR) is obtained by measuring at 230 ° C. and a load of 2.16 kg in accordance with ASTM-D1238. If the MFR is less than 0.1 g / 10 min, molding is difficult, and if it exceeds 50 g / 10 min, the mechanical properties are insufficient. In order to obtain a better balance between moldability and mechanical properties, the MFR is more preferably in the range of 0.2 to 30 g / 10 min.

Moreover, as a copolymer (B) which consists of propylene and ethylene or a C3-C20 alpha olefin in this invention, Shore A hardness (ASTM-D2240) is 65-90, melting | fusing point is 130-170 degreeC, A material having a density (ASTM-D1505) of 860 to 875 kg / m ³ and a glass transition temperature by DSC measurement of −35 ° C. to −25 ° C. is used.

  Examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and the like can be mentioned, and those having a melt flow rate (MFR) of 1 to 15 g / 10 min are particularly preferable, and more preferably in the range of 3 to 10 g / 10 min. It is more preferable that

  The Shore A hardness used in the present invention is a press molding condition of a temperature of 190 ° C., a heating and pressing time of 7 minutes, and cooling with a 15 ° C. chiller. After placement, a rubber hardness tester (Shore A type) was used to superimpose two sheets, and the scale was read immediately after contact with the pressing needle (according to ASTM-D2240). The Shore A hardness (ASTM-D2240) of the copolymer (B) comprising propylene and ethylene or an α-olefin having 3 to 20 carbon atoms in the present invention is preferably 65 to 85, and more preferably in the range of 72 to 85. Are preferred.

  The melting point used in the present invention is about 10 mg of a sample packed in an aluminum pan, (i) heated to 200 ° C. at 100 ° C./min and held at 200 ° C. for 5 minutes (ii) at −10 ° C./min It is obtained by measuring the temperature of the endothermic peak observed in (iii) when the temperature is lowered to 10 ° C. and then (iii) the temperature is raised to 200 ° C. at 10 ° C./min. In the present invention, the copolymer (B) composed of propylene and ethylene or an α-olefin having 3 to 20 carbon atoms has a melting point in the range of 130 to 170 ° C, more preferably 130 to 150 ° C. .

  The density used in the present invention is measured by a method based on ASTM-D1505 after a 2 mmt press sheet obtained under the same press molding conditions as the Shore A hardness measurement sample is allowed to stand at 23 ° C. for 72 hours. Is obtained. In the present invention, the density of the copolymer (B) comprising propylene and ethylene or an α-olefin having 3 to 20 carbon atoms is in the range of 860 to 875 kg / m3, more preferably 860 to 872 kg / m3. Is preferred.

  The glass transition temperature by DSC measurement used in the present invention is about 10 mg of a sample packed in a dedicated aluminum pan, (i) heated to 200 ° C. at 100 ° C./min and held at 200 ° C. for 5 minutes (ii) The temperature is lowered to −100 ° C. at 10 ° C./min and held for 5 minutes, and then (iii) the temperature is raised at 10 ° C./min. It is obtained by obtaining from the DSC curve at the time of (iii). The glass transition temperature of the copolymer (B) composed of propylene and ethylene or an α-olefin having 3 to 20 carbon atoms in the present invention is in the range of −35 ° C. to −25 ° C., and further −33 ° C. The thing of -26 degreeC is preferable.

  As described above, the copolymer (B) composed of propylene of the present invention and ethylene or an α-olefin having 3 to 20 carbon atoms is not particularly limited as long as it satisfies the above physical properties, but is commercially available, for example. May be used. Examples of commercially available products include “Notio (registered trademark)” manufactured by Mitsui Chemicals, Inc. and “Tough Selenium (registered trademark)” manufactured by Sumitomo Chemical Co., Ltd., but are not limited thereto.

  The transparent polypropylene resin layer 4 in the present invention is made of a biaxially stretched sheet. The draw ratio in the MD direction and the TD direction is not particularly defined in the present invention, but a draw ratio of about 2 to 20 times is desirable, more preferably about 3 to 10 times. If the draw ratio is low, the toughness of the film is relatively low. Conversely, if the draw ratio is high, the shrinkage and curl of the sheet may increase due to the heat history after film formation. When a so-called uniaxially stretched polypropylene film that is stretched in only one of the MD direction or the TD direction is used, high toughness is obtained in the stretching direction, but the unstretched direction In contrast, high toughness cannot be obtained. Therefore, when the bending process in the unstretched direction is performed, whitening or cracking of the bent portion occurs.

  The method of laminating the transparent polypropylene resin layer 4 in the present invention may be performed using a known method, and is not particularly limited, but a dry laminating method, a wet laminating method, a sand laminating method or the like is preferably used. It is done. The film formation and bonding of the transparent polypropylene resin layer 4 may be performed in-line at one time, or may be once wound after film formation and then bonded again.

  As a method of providing the concave embossed pattern 5 provided as appropriate in the present invention, a transparent polypropylene resin layer 4 formed by melt extrusion and biaxial stretching from a T-die extruder is bonded via the adhesive layer 3. After the adhesive is cured by aging, the concave embossed pattern 5 is applied to the surface layer using a heat drum having a pattern in which the concave / convex pattern is reversed from the concave pattern to be applied.

  The surface protective layer 6 in the present invention can be provided by providing the concave embossed pattern 5 and then laminating the outermost layer using a technique such as a gravure printing method. For the purpose of increasing the adhesion at the laminated interface, it is also necessary to introduce a polar group into the laminated interface by a known technique such as corona treatment. Especially when using a polypropylene resin which is a nonpolar resin, the corona treatment is necessary. The polar group introduction by such as is preferably performed.

  The order of applying the concave embossed pattern 5 and laminating the surface protective layer 6 can be reversed. In that case, since the surface protective layer firmly enters the recessed portion, the ability to maintain the weather resistance of the recessed portion is exhibited, and further improvement of the weather resistance can be expected. The substrate sheet 1 may be transparent, but a colored sheet to which a pigment or the like is added may be used so as not to show the texture of the substrate such as a steel plate to be bonded.

  As a material used for the surface protective layer 6 of the present invention, specifically, in a resin by reacting a prepolymer in which a hydroxyl group is introduced into an acrylic resin or an ester resin with a separately prepared curing agent having an isocyanate group. It is better to cure by generating a urethane reaction product. As the isocyanate component, an aromatic component may be used if importance is attached to immediate curing, and an aliphatic component may be used if importance is placed on ultraviolet resistance. Moreover, when it is desired to impart flexibility to the surface protective layer, a method of modifying the urethane from a prepolymer state is also preferably used.

  As a method of curing the surface protective layer 6, in addition to a method of reacting with isocyanate (isocyanate curing method), a method of irradiating ultraviolet rays after adding a photopolymerization initiator (ultraviolet curing method), a method of irradiating an electron beam (Electron curing) may be used. A plurality of these curing methods may be combined.

  The surface protective layer 6 generally uses various weathering stabilizers. For example, benzotriazoles, benzoates, benzophenones, hydroxyphenyltriazines, etc. are suitably used as UV absorbers, and hindered amines are preferably used as light stabilizers, and these are used alone or in combination. . Further, the gloss can be adjusted by adding finely pulverized silica, and the scratch resistance can be improved by adding glass-based beads. It is also preferable to add a slip agent to prevent sheet blocking, or to add an antistatic agent to suppress adhesion of dust and the like.

  The lamination method of the surface protective layer 6 should just use a well-known technique, and although it is not limited at all, the gravure coating method is generally used. The thickness is preferably about 3 to 20 μm. However, in the case of the gravure coating method, the film thickness that can be coated at one time is about several μm. If the thickness is larger than that, problems such as uneven coating may occur. In that case, a method of repeatedly coating a desired thickness in a plurality of times is preferably used.

  The total thickness of the decorative sheet of the present invention thus obtained is preferably 40 to 300 μm. When the total thickness of the decorative sheet is less than 40 μm, it is not possible to select a concave embossed pattern with a very deep depth, which limits the design. In addition, the absolute addition amount of the UV absorber, which is one of the additives that are normally added to the transparent polypropylene resin layer 4 and the surface protective layer 6 in the decorative sheet, is reduced, and the transparent polypropylene resin layer 4 Moreover, since the ratio of the surface area compared with the volume of the surface protective layer 6 becomes high, precipitation of an ultraviolet absorber will be accelerated | stimulated and a weather resistance performance will fall. If the total thickness of the decorative sheet is secured to 40 μm or more, these problems can be avoided.

  On the other hand, when the total thickness of the decorative sheet exceeds 300 μm, the rigidity as the sheet becomes too high, and the flexibility imparting effect according to the above (1) and (2) and biaxial stretching of the present invention. The effect of imparting toughness is not sufficiently exhibited, and the design of the bent portion in the post-bending process is lowered. In addition, since the raw material increases in proportion to the thickness of the decorative sheet, it is not very economical. If the total thickness of the decorative sheet is suppressed to 300 μm or less, these problems can be avoided.

  The steel sheet decorative board produced using this decorative sheet was bonded to a steel sheet base material, etc., and when subjected to post-processing such as bending, design changes such as whitening and cracking of the bent portion were suppressed. It will be a thing.

  A resin obtained by adding 6% by weight of an inorganic pigment, 0.2% by weight of a phenolic antioxidant, 0.3% by weight of a hindered amine light stabilizer, and 0.2% by weight of an antiblocking agent to a random polypropylene resin, Using a die extruder, a colored sheet was prepared by melt extrusion from a T-die at an extrusion temperature of 230 ° C. and an extrusion thickness of 70 μm, and both the surfaces of the sheet were subjected to corona treatment, followed by pattern ink (Toyo Ink). A wood grain pattern was applied using Manufacture Co., Ltd. (Lamister) to form a pattern layer.

  Further, a two-component curable dry laminating adhesive (manufactured by Mitsui Chemicals Polyurethanes Co., Ltd .; Takelac A-520 (main agent), Takenate A-80 (hardener)) on the wood grain pattern layer is used as the main agent / hardener. = 9/1 blended, adjusted to 30% solids with ethyl acetate solvent, then coated to a solid content thickness of about 5μm by gravure printing and dried in an oven at 60 ° C for 2 minutes The solvent component was volatilized.

  On the other hand, a homopolypropylene resin having an isotactic pentad fraction of 70%: Prime TPO F-3900 (manufactured by Prime Polymer Co., Ltd., MFR = 4.5), 80% by weight, propylene and ethylene or carbon number As a copolymer composed of 3 to 20 α-olefin, Notio PN-2070 (manufactured by Mitsui Chemicals, MFR = 7.0) is 19% by weight, and Tinuvin 326 (Ciba Japan) is used as an ultraviolet absorber. Made by adding 0.5% by weight of Kimasorb 2020 (manufactured by Ciba Japan Co., Ltd.) as a light stabilizer, and melt extrusion at an extrusion temperature of 230 ° C. from a T-die. After cooling and solidification, stretch about 4 times in the film forming direction (MD direction) and about 5 times in the direction perpendicular to the film forming direction (TD direction) while applying a thermal history. There was obtained a transparent polypropylene resin sheet of biaxially stretched.

  Notio PN-2070 has a propylene-derived structural unit content of 71 mol%, and contains a structural unit derived from ethylene and a structural unit derived from 1-butene as a structural unit other than the structural unit derived from propylene. It is. Its physical properties are 75 for Shore A hardness (ASTM-D2240), 138 ° C for melting point, 867 kg / m3 for density (ASTM-D1505), and -29 ° C for glass transition temperature (Tg).

At this time, the number of screw rotations of the extruder was adjusted to produce sheets with the stretched transparent polypropylene resin sheet thickness set to 80 μm, 130 μm, 180 μm, and 230 μm, respectively.

  After corona treatment was performed on one side of each of these transparent polypropylene resin sheets, the corona treatment surface side and the adhesive surface were bonded together and pressure-bonded using a nip roll. Thereafter, aging was performed for 72 hours in an environment of 60 ° C. In the sheet after completion of aging, the outermost surface layer on the transparent polypropylene resin layer side is subjected to corona treatment again, and a surface protective layer (manufactured by DIC: UC Clear) is laminated with a thickness of 6 μm using a gravure coating method. Aging was further performed for 72 hours in an environment at 0 ° C. Thus, the decorative sheet of Examples 1-4 was obtained. At this time, a decorative sheet produced using a stretched transparent polypropylene resin sheet having a thickness of 80 μm is Example 1, and a sheet using a sheet of 130 μm is used in Example 2, and a sheet of 180 μm is used. Is Example 3, and Example 4 uses a 230 μm sheet.

  A heat drum provided with a protrusion pattern (a reverse of the unevenness of the wood conduit pattern applied to the decorative sheet) was heated to 90 ° C., and further niped with a silicon nip roll, and then the nip portion was subjected to Example 1 The decorative sheet of Examples 5 to 8 was obtained by giving a concave pattern with a wood grain tone through the decorative sheet. At this time, the decorative sheet of Example 1 was provided with a grained concave pattern in Example 5, and the example in which a concave pattern was added to Example 2 below provided Example 6 and Example 3 with a concave pattern. Example 8 was obtained by giving a concave pattern to Example 7 and Example 4.

  The thickness of each decorative sheet in Examples 1 to 8 was measured using a film thickness measuring device TH-102 A type (manufactured by Tester Sangyo Co., Ltd.). The results are shown in Table 1.

  After applying an adhesive for olefin and steel plate (manufactured by Hitachi Chemical Polymer Co., Ltd .: Hibon) on a steel plate substrate having a thickness of 0.7 mm whose surface layer has been galvanized, with heat of 180 ° C. After heating for 3 minutes to activate the adhesive, the decorative sheets described in Examples 1 to 8 were laminated while being nipped with a silicon roll, and cooled with cooling water immediately after the lamination, and then the decorative sheet surface layer By removing the moisture, the steel sheet decorative plates of Examples 9 to 16 were obtained. The steel sheet decorative board produced using the decorative sheet of Example 1 is Example 9, the steel sheet decorative board produced using the decorative sheet of Example 2 is Example 10, and the correspondence between the decorative sheet and the steel sheet decorative board is shown below. Example 3 is Example 11, Example 4 is Example 12, Example 5 is Example 13, Example 6 is Example 14, Example 7 is Example 15, Example 8 is Example 16. is there.

<Comparative Example 1>
Except that Prime TPO F-3900 (manufactured by Prime Polymer Co., Ltd., MFR = 4.5) was 99% by weight and Notio PN-2070 (Mitsui Chemicals Co., Ltd., MFR = 7.0) was not added. Using the same method as in Example 1, the decorative sheet described in Comparative Example 1 was obtained.

<Comparative example 2>
A decorative sheet described in Comparative Example 2 was obtained using the same method as in Example 1 except that the film was stretched about 4 times only in the film forming direction (MD direction) by the uniaxial stretching method.

<Comparative Example 3>
After being extruded from the T-die, the decorative sheet described in Comparative Example 3 was obtained using the same method as in Example 1 except that the film was not stretched and not stretched.

<Comparative example 4>
A concave pattern was applied to the decorative sheet of Comparative Example 1 in the same manner as in Examples 5 to 8, and the decorative sheet of Comparative Example 4 was obtained. Similarly, decorative sheets of Comparative Example 2 to Comparative Example 5 and decorative sheets of Comparative Example 3 to Comparative Example 6 were obtained. The above comparative examples were measured in the same manner as in the examples. The results are shown in Table 2.

  Adhesive activity by applying an adhesive for olefin and steel plate (manufactured by Hitachi Chemical Polymer Co., Ltd .: Hibon) on a 0.7 mm thick steel plate substrate at a coating thickness of 20 μm, followed by heating at 180 ° C. for 3 minutes. After being laminated, the decorative sheets described in Comparative Examples 1 to 3 are laminated while being niped with a silicon roll, and cooled with cooling water immediately after the lamination, and then the moisture on the decorative plate surface layer is removed, The steel sheet decorative plates of Comparative Examples 7 to 12 were obtained. The steel sheet decorative board produced using the decorative sheet of Comparative Example 1 is Comparative Example 7 and the steel sheet decorative board produced using the decorative sheet of Comparative Example 2 is Comparative Example 8, and the following will correspond in the same order. The steel sheet decorative board produced using the decorative sheet of Comparative Example 6 is Comparative Example 12.

<Performance comparison>
The steel sheet decorative plates of Examples 9 to 16 and Comparative Examples 4 to 6 thus obtained were bent. The bending process conditions were an ambient temperature level 2 (5 ° C., 25 ° C.) and a bending direction level 2 (MD direction bending, TD direction bending). The bending angle was an L-shaped bend of 90 ° (however, the decorative sheet side should be the outer surface). A specific bending method was performed by cutting each steel sheet decorative plate into a size of 50 mm × 50 mm, setting a sample between an L-shaped acute angle jig and an obtuse angle jig, and air-pressing with a press. Table 3 shows the results of relative evaluation of the degree of whitening and cracking of the bent portion.

  As can be seen from the table, the decorative sheet of the present invention is superior in folding processability to the decorative sheet shown in the comparative example. Moreover, the tendency which the bending workability to the extending | stretching direction is generally good is acquired. In addition, as for the sheet thickness, the tendency to bend better when the film thickness is reduced.

  Since the decorative sheet of the present invention does not use any vinyl chloride, there is no concern about environmental problems. Furthermore, when the decorative sheet of the present invention is bonded to a steel plate substrate and the like is subjected to a bending process, a decorative sheet that does not deteriorate in design properties such as cracking or whitening of the decorative sheet can be provided.

DESCRIPTION OF SYMBOLS 1 ... Base material sheet 2 ... Pattern layer 3 ... Adhesive layer 4 ... Transparent polypropylene resin layer 5 ... Recessed embossing process 6 ... Surface protective layer

Claims (4)

In the decorative sheet having a pattern layer, a transparent polypropylene resin layer, and a surface protective layer in this order on the base sheet,
(1) The transparent polypropylene resin layer is
A homopolypropylene resin (A) having an isotactic pentad fraction of 75% or less, which is defined as the number of propylene monomers having 5 consecutive methyl groups and facing in the same direction / the number of propylene monomers × 100 [%]; It consists of a copolymer (B) composed of propylene and ethylene or an α-olefin having 3 to 20 carbon atoms, and the blending ratio of (A) and (B) is 50/50 to 95/5,
(2) A copolymer (B) comprising the propylene and ethylene or an α-olefin having 3 to 20 carbon atoms,
Shore A hardness (ASTM-D2240) is 65 to 90, melting point is 130 to 170 ° C, density (ASTM-D1505) is 860 to 875 kg / m ³ , and glass transition temperature by DSC measurement is -35 ° C to -25 ° C. ,
(3) The decorative sheet, wherein the transparent polypropylene resin layer is a biaxially stretched sheet.
Yes.   The decorative sheet according to claim 1, wherein the decorative sheet has a total thickness of 40 to 300 μm.   3. The transparent polypropylene resin layer is subjected to a stretching process in a direction perpendicular to the film forming direction and the film forming direction after being extruded from the T die by a biaxial stretching method. The manufacturing method of the decorative sheet in any one.   The method for producing a decorative sheet according to claim 3, wherein the transparent polypropylene resin layer is subjected to a concave embossed pattern treatment from the surface side after the stretching treatment.

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